Optical and electronic properties of sputtered hydrogenated amorphous silicon-tin alloys

Abstract
Hydrogenated amorphous silicon‐tin alloys (a‐Si1−xSnx: H), in the composition range 0≤x≤0.51, have been prepared by rf sputtering. It is shown that the addition of Sn moves the conduction‐band edge, thereby closing the optical band gap. The dc dark conductivity increases less than expected, with increasing Sn content, based on a simple decrease in band gap. This and the temperature dependence of the dark conductivity suggest a transition from extended‐state free‐carrier conduction to localized‐state hopping conduction. Photoluminescence measurements show the presence of defect‐state radiative recombination.